So here's my problem with the new system. When I am recirculating my 2" RIMS works great. When I am stepping temps and recirculating fast it works great. But when I am heating my on demand sparge water when the ground water is this cold, or when I'm stepping temps on a sticky (I love rye and wheat) mash the RIMS boils.
From what I can tell through some experimentation with plain water it's a function of the water in the tube not mixing well enough. At higher flow rates the PID's PV pretty much exactly matches the output temp, but at lower flow rates the PV is way below the output temp when trying to make a large (>10 F) step. I have a suspicion that the real cause is a lack of turbulent flow at the lower speeds, leaving a pocket of cool water around the temp probe.
I believe that the 1.5" Brewershardware.com triclover RIMS would solve my problems. On the other hand, I think that stepping down to a 1.5" DIY setup in the same style I have now would do the same thing. Also, I was contemplating putting a T on the RIMS output, running a line back to a T on the pump input, essentially creating a loop that would allow full pump flow over the RIMS, but allowing me to throttle the output. So far I have read nothing but great things about the triclover RIMS, and it seems to be a much better design than any of the DIY setups I've seen.
I'm totally conflicted on spending $90 for the fittings for the return loop, $100 for smaller fittings for the RIMS, or just bucking up the $200 for the triclover RIMS. I don't want to go with a new RIMS if the return loop will fix the problem, but then again, I don't want to waste $$ on fittings that aren't going to fix my problem. If any of you have experience with this please let me know what you think.